The Internet is a good example of a traditional IP (Internet Protocol) network. An IP network is a packet switched network wherein data packets are routed between nodes of a network from a sending node to a receiving node. IP networks operate on a per-hop basis, whereby packets are routed from one node to the next depending on various criteria, for example traffic, desired QoS (Quality of Service) etc. Traditionally, the Internet has been comprised of a network and/or a plurality of sub-networks of fixed computers connected by wired connections.
A so-called MIP (Mobile IP) network expands these principles to also take into account a situation when some of the nodes are no longer fixed and are able to move to different points in the IP network. Such nodes are referred to as MNs (Mobile Nodes). Furthermore, with the rapid development of wireless communication networks, it is possible to have wireless nodes which form part of the network.
A so-called DNS (Domain Name System) stores mappings of an IP address to a logical name, which can be easily remembered, for example a humanly-readable name usually called the FQDN (Fully Qualified Domain Name). That is the IP address is the physical address of a particular node in a network, and therefore the DNS can be thought of as comprising a mapping between a physical address of the host and a logical name given to that host which can be easily remembered. If a host wants to be reachable at a particular IP address, then an entry needs to be present in the DNS, which maps the FQDN to the IP address currently configured on the host. However, if the host is a MN, then the IP address changes whenever the MN moves and attaches to a different network.
One way of handling this is disclosed in the IETF (Internet Engineering Task Force) draft entitled “Mobility Support in IPv6” by D. Johnson et al, published in June 2003, which assumes that the HoA (home address) of the MN does not change and the MN can always be reached by its HoA, irrespective of where the MN currently is and what CoA (Care of address) it has configured. In this case, the MN's HoA is mapped with its FQDN in a DNS entry. However, the disadvantage of this is evident when employed in cdma2000 networks, wherein there is a requirement to support dynamic HoA configuration for a mobile node. In this situation, in order for the mobile node to be reachable at the newly configured HoA, the DNS entry which corresponds to the mobile node needs to be updated with the newly configured HoA.
Thus at least one aim of embodiments of the present invention is to have a mechanism for updating the DNS entry corresponding to a MN.
That is, if a MN configures a new HoA or configures a HoA for the first time, then the MN is not reachable at its newly configured HoA unless the DNS entry that corresponds to the MN is updated. Furthermore, the DNS update needs to be performed in a secure manner in order to prevent malicious modification to the DNS entries. For the MN to send a dynamic DNS update, it is preferred to have a security association with the DNS server. It is undesirable to have a security association between the DNS servers and every MN, since this is not scaleable. Also, a MN could potentially have multiple HoA's configured.
Therefore it is another aim of embodiments of the present invention for the MN to dynamically update the DNS entry in a secure and scaleable manner.
Furthermore, since a MN could potentially have multiple HoA's configured, the current standards do not make it possible for the MN to selectively indicate the HoA at which it wants to be reachable. Embodiments of the present invention provides a further advantage in that it allows the MN to selectively indicate which HoA it wants to be reachable at.
The IETF standards RFC 2136 of April 1997 and RFC 3007 of November 2003, both describe a DNS update message that can be sent by a node to a DNS server to update a DNS entry for a particular FQDN. However, neither of these documents deals with updating DNS entries for MNs. Also, these documents do not describe how security associations may be handled between the mobile nodes and the DNS system.